DM-COP8/20D National Semiconductor, DM-COP8/20D Datasheet - Page 26

• Manufacturer Part Number: DM-COP8/20D
• Description: CABLE FOR DEBUG MODULE 20-DIP
• Manufacturer: National Semiconductor

Specifications of DM-COP8/20D

• Accessory Type: 20-DIP Target Cable
• For Use With/related Products: MetaLink Debug Module
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *DM-COP8/20D

However, the accumulator-based machine requires operands to be moved into the
accumulator before instructions are executed. Which takes longer in the end? It depends
on how much faster an accumulator-based machine can execute an instruction than a
register-based machine.
Trade-off memory efficiency—An accumulator-based machine will generally have
shorter opcodes than a register-based machine.
Interrupts
Interrupt is an event which causes the microcontroller to stop executing code in its
normal sequence and instead respond to the occurrence of the event. The microcontroller
performs the following steps when an interrupt occurs:
1-14
MICROCONTROLLER BASICS
1. Stops execution of the "next" instruction.
2. Disables additional interrupts.
3. Saves current status of the microcontroller.
4. Jumps to a special interrupt handling routine.
5. Returns from the special interrupt handling routine.
6. Restores state of the microcontroller
7. Enables interrupts
8. Executes the "next" instruction.
Figure 1-6 Adding Two Numbers Using Register Based Machine
Addent #1
Addent #2
Register 1
Register 2
Register 3
A
ALU